Etching gases and cleaning gases are to manufacture semiconductors. For example, chemical vapor deposition (CVD) and plasma enhanced chemical vapor deposition (PECVD) chambers need to be regularly cleaned to remove deposits from the chamber walls and platens. This cleaning process reduces the productive capacity of the chamber since the chamber is out of active service during a cleaning cycle. The cleaning process may include, for example, the evacuation of reactant gases and their replacement with a cleaning gas, activation of that gas, followed by a flushing step to remove the cleaning gas from the chamber using an inert carrier gas. The cleaning gases typically work by etching the contaminant build-up from the interior surfaces, thus the etching rate of the cleaning gas is an important parameter in the utility and commercial use of the gases, and some cleaning gases can also be used as etching gases. In addition, present cleaning gases have significant amounts of components with high global warming potentials. For example, U.S. Pat. No. 6,449,521 discloses a mixture of 54% oxygen, 40% perfluoroethane and 6% NF3 as a cleaning gas for CVD chambers. However, perfluoroethane has a relatively high GWP, estimated to be on the order of 6200 at a time horizon of 20 years, and 14000 at a time horizon of 500 years. Other cleaning gases include C3F8, which also has a significant global warming potential. Other gases include, for example, those described in U.S. Pat. No. 6,242,359, which discloses unsaturated flurorine containing oxides, e.g. hexafluoropropene oxide (CF3CFOCF2), perfluoropropane-dial (CFOCF2CFO), trifluoromethanol (CF3OH), difluoromethanol (CHF2OH), difluorooxyfluoromethane (CHF2OF), perfluorodiethyl ether (C2F5OC2F5), 1,1,3,3-tetrafluorodimethyl ether (CHF2OCHF2), and the like. Moreover, even when processes are optimized, there is the potential for release of the cleaning gases. Finally, given the chemical stability of these gases, their activation can be energy intensive. A variety of reactors are useful in producing semiconductors using etching and cleaning gases.
Etching gases are used to etch structures into semiconductors. The gases are introduced into the chambers, converted into plasma, and then the plasma reacts with the exposed surface of a masked semiconductor to remove the exposed material from a film deposited on a substrate. The gases can be selective for the given film over a particular substrate. For example, CF4/O2, SF6, and CHF3 may be used to etch polysilicon, CF4, CF4/O2 and CH2F2 may be used in etching Si3N4 films.
However, it is understood that that these gases may generate relatively high amounts of toxic waste gases, which may pose additional GWP or Environmental, Health, and Safety (EHS) issues apart from the GWP of the cleaning or etch gas itself. Thus, there is a need in the art to reduce the harm of global warming caused by the cleaning and operation of CVD reactors with an effective and inexpensive cleaning/etching gas that has a high etch rate and a lower GWP and ESH impact than incumbent gases.